Bay 12 Games Forum

Its a serie of 13 one-tile iron bridge, that, when activated, form 13 pillars. It prevent lava left-over on the 13 tiles where I cannot put grates.

EDIT:  Oh yea!  I can't quite tell from the map.  What are the tiles in the middle of the channel where the goblins walk.  I mean the tiles that all those grates are anchored to.  I was thinking just regular floor tiles, but wouldn't some magma stay on top (at depth 1) on those tiles then?  I must be missing something then.  Anyone have an answer?

Doubly EDIT: Nvm, fortifications, duh!  I couldn't tell from the map, but when I looked at the video again I could tell what they were.

Nope, not fortifications, its bridges that can be raised when I use the trap.
The goal is to avoid leftover magma, as you guessed, but I can lower them afterward to allow access to caravans.
I was forced to put pillars under those central tiles because grates cannot support other grates, and the center tiles kept collapsing.

The history of this trap construction is full of mistakes and time waste. Here are some:

-At start, the lenght was nearly one third of what it is today! The trap was working,  but I had a hard time catching more than a couple gobs without them going trough before the gates were closed.
When I understood I would have to greatly extend the lenght, I got depressed by the huge amount of work needed. The first part was hours and hours of work, and I had to do more than double that! That nearly put a definitive stop on it, and it took me 6 months to finally start working again, and a few weeks later, tadaaa!

-Once, after testing the trap and loading in with lava, I forgot to forbid the door leading to the reservoir. Of course, while I was not looking, a dwarf working on the pumps at that level opened it (what for???) and burned alive. The side effect was that the spilled lava blocked the way and two more worker nearly starved to death.

-The most awful huge astounding horrible mistake I did was when I installed the pumps. I had already tried the stacking method, so I knew what I was doing. Copying what I did before, I designed the walls, floor, for hours, then put the pumps, with my fingers sores from the repetitive task done hundreds of times.
Then I test-fired it. And nothing happened...
I realised I had forgotten one little thing... to put a hole under each pump so they transfer power to each other! And removing the floor afterward did NOT repair it! I had to deconstruct and rebuild EACH pump!! And the worse is, I already did the same mistake when I built the first part of the trap! I KNEW this mistake, and I did it again! Aaarghh!

-Of course, I had numerous case of stupid dwarves blockinf themselves when deconstructing floor, building wall that prevented the construction of other pieces of wall, etc... I also had some cases of cave-in, the most stupid one was when I deconstructed a floor, and realised that floor are not linked to bridges... So I had half a dozen square of floor, adjacent to a bridge and nothing else, falling throught the iron floor grates, the bottom cistern, and the workshops under it...

I finished! At last!
After 10 years of construction, several miscalculations, redesign, mistakes, it's finally completed!

And what is it exactly?
Well its a re-usable, fast cycling, lava trap, that leave behind only the metallic weapons and armor ready to be melted. Its large enough to allow caravans to come, long enough to trap ennemies easily, its the perfect fortress entrance!

Here come the links to the map and a video in use:
Map: http://mkv25.net/dfma/poi-21036-thetrap
Video: http://mkv25.net/dfma/movie-1931-theultimatelavatrap

Here are some numbers:
160 green glass pumps
161 service doors
36 gear assembly
63 water wheels (26 needed only, I went a little overkill on the powerplant)
104 iron grates
19 iron bridges
10 years of construction
8 deaths from accidental cave-in, lava, ambush and other mishaps.


If you have questions about it, I will gladly answer them.
Hope you enjoy it 

What the hell is it doing there? O_O
Well, my bad, I was sure I never built one, because I simply never tried all the metal crafting before the magma forge.

Still, its anormal that the last item of each work order goes on the basic forge. I will deconstruct it and no doubt i will not have any more problems.

I never built a basic forge, I started with a magma one.
It's 100% sure: no old forge, only magma.

I tested a little, and its obvious it is a bug:
Every time I put a work order to forge, it will forge all the items but the last, for wich it will ask a refined coal.
If I make the last item by manually adding it to a magma forge, it will be forged without problem, but the work order will not be validated (maybe normal?).